The present invention relates to a vehicular lamp which includes a lamp body in which is mounted a reflector holding a light source, and which permits adjustment of the angle of the optical axis of the lamp by tilting the reflector.
A headlamp used in vehicles such as automobiles generally is provided with an aiming adjustment mechanism for adjusting the optical axis of a reflector mounted within a lamp body by vertically and laterally tilting the reflector. Headlamps used in some vehicles have a mechanism for automatic leveling the optical axis of the headlamp so that the optical axis is maintained at a predetermined angle relative to the road surface despite tilting motion of the vehicle. In either case the angular adjustment of the optical axis requires the provision of a reflector tilting device capable of tilting either the entire lamp or a reflector disposed within a lamp body.
A reflector tilting device in the case of a lamp in which only the reflector is tilted may be designed such that the reflector is supported on at least one fulcrum so as to be tiltable with respect to the lamp body along a direction required for the adjustment of the optical axis, for example, vertically or laterally. A tilting actuator is disposed at a location other than the fulcrum to displace the reflector along the direction in which it is tiltable. Thereby the reflector is displaced in a required direction so that the aiming angle thereof is adjusted.
In the construction wherein the tilting actuator displaces the reflector, the tilting actuator undergoes a rectilinear motion while the reflector is rotated about the fulcrum. It is necessary in such a case to employ, at the location where the tilting actuator is coupled to the reflector, a connection structure that hinders neither the rectilinear motion of the tilting actuator nor the rotational motion of the reflector. For such a connection structure there has conventionally been employed a ball bearing body in the shape of a groove (hereinafter referred to as a groove-type ball bearing body). FIG. 7 illustrates the overall structure of such a groove-type ball bearing body.
Referring to FIG. 7, a reflector 3 contained in a lamp body 1 can vertically be tilted on a fulcrum (not shown), and a tilting actuator 31 is secured to the lamp body 1 at a location facing the rear surface of the reflector 3. An actuator rod 32 having at its leading end a spherical leading end portion 33 protrudes from the tilting actuator 31 in the direction of the optical axis of the lamp. The tilting actuator 31 is designed to reciprocally displace the actuator rod 32 in the direction of protrusion when driven. A stem 3b protrudes integrally from the rear surface of the reflector 3 at a location facing the actuator rod 32. A groove-type ball bearing body 21A is secured to a leading end of the stem 3b by a screw 7.
As is apparent from the enlarged perspective view in FIG. 8A, the groove-type ball bearing body 21A, which is plastic-molded, has a semicylindrical groove portion 22, a pair of engagement strip portions 23, and stationary portions 25. The engagement strip portions 23 are formed to protrude on opposed sides along the direction of the groove of the groove portion 22 and have leading end strips 24 bent at an acute angle towards the groove portion 22. The stationary portions 25 protrude outwardly from bases of the engagement strip portions 23. Using small holes 26 formed in the stationary portions 25, the groove-type ball bearing body 21A is secured to the reflector 3 by the screw 7 so that the opening side of the groove portion 22 is directed towards the tilting actuator 31. As is apparent from the longitudinal sectional view in FIG. 8B, the spherical leading end portion 33 of the actuator rod 32 is fitted in a gap formed between the groove portion 22 and the leading end strips 24 of a pair of the engagement strip portions 23. In this state, the inner bottom surface of the groove portion 22 and a pair of the leading end strips 24 abut the spherical surface of the spherical leading end portion 33, and the spherical leading end portion 33 is supported at those abutment points in such a manner as to allow spherical motion.
In this structure, since the groove portion 22 and the engagement strip portions 23 are constant in sectional shape along the direction of the groove, the spherical leading end portion 33 is provided with a degree of freedom in moving in the direction of the groove. Accordingly, if the actuator rod 32 is reciprocally displaced by the tilting actuator 31 in the direction of the optical axis, the groove-type ball bearing body 21A secured to the reflector 3 is displaced in the direction of the optical axis in accordance with the displacement of the spherical leading end portion 33. Since the spherical leading end portion 33 has a margin formed in the direction of the groove of the groove portion 22, the reflector 3 is tiltable with respect to the actuator rod 32 in a required direction, vertically in this case.
The groove-type ball bearing body 21A is plastic-molded as described above and designed such that the molding die is drafted in the direction of the groove of the groove portion 22. Therefore the groove portion 22 and the engagement strip portions 23 are constant in sectional shape along the direction of the groove. Also, the groove portion 22 has opposed open ends. Hence, if the reflector 3 has been tilted greatly, that is, if the spherical leading end portion 33 has been tilted to a large angular position relative to the groove-type ball bearing body 21A, there is a concern, as illustrated in FIG. 8C, that the spherical leading end portion 33 might slide to one open end of the groove portion 22, be removed through the gap between the groove portion 22 and the engagement strip portions 23, and drop from the groove-type ball bearing body 21A. If the spherical leading end portion 33 has been disengaged in this manner, the reflector cannot thereafter be tilted, which makes the automatic leveling adjustment of the optical axis impossible.
Also, the spherical leading end portion 33 tends to drop from the groove-type ball bearing body 21A when the actuator is removed from the lamp body during assembly of or maintenance on the actuator. Once the spherical leading end portion 33 has dropped from the groove-type ball bearing body 21A, it becomes difficult to fit the spherical leading end portion into the groove-type ball bearing body from the side of the actuator. This causes a problem of deterioration in workability.
It is an object of the present invention to provide a vehicular lamp having a reflector tilting device which prevents a spherical leading end portion of a tilting actuator from dropping out of a reflector-side groove-type ball bearing body.
In accordance with this and other objects, the invention provides a vehicular lamp in which a reflector tilting device capable of tilting a reflector mounted in a lamp body includes a tilting actuator disposed in the lamp body and having an actuator rod displacable along the direction of the optical axis of the reflector and a groove-type ball bearing body mounted to the reflector and fitted to a spherical leading end portion provided at a leading end of the actuator rod. The groove-type ball bearing body has a groove portion which has two open ends and into which the spherical leading end portion is fitted, an engagement strip portion disposed to cover the groove portion from either side and engaging the spherical leading end portion on a front side of the groove portion, and a dropout-preventing portion formed at either side of the groove portion protruding towards the interior of the groove portion and preventing the spherical leading end portion from dropping from either open end of the groove portion.
In this construction, a pair of engagement strip portions are provided facing each other on opposed sides along the direction of the groove of the groove portion, and the respective engagement strip portions have leading end strips supported at one end and folded back towards the groove portion. The respective leading end strips are wedge-shaped so that the distance therebetween gradually decreases towards the groove portion. Further, the dropout-preventing strip portions provided at opposed ends in the direction of the groove of the groove portion are provided at opposed locations of the groove portion and do not cross the direction of the groove portion. The spherical leading end portion may be provided with a precut portion corresponding in shape to a part of the dropout-preventing strip portion protruding into the groove, and the spherical leading end portion can be inserted into the groove portion with the precut portion facing the dropout-preventing strip portion.
In accordance with the present invention, even in the case where the reflector is tilted greatly or the actuator rod forms a large angle with respect to the reflector, for example, when removing the tilting actuator, to such an extent that the spherical leading end portion is displaced to one of the ends of the groove portion of the groove-type ball bearing body, the spherical leading end portion is prevented from dropping from either open end of the groove portion. As a result, the actuator rod remains fitted to the reflector, and the tilting motion of the reflector is ensured.